U.S. patent application number 17/365323 was filed with the patent office on 2021-10-21 for piezoelectric pump.
The applicant listed for this patent is Murata Manufacturing Co., Ltd.. Invention is credited to Masaaki FUJISAKI, Nobuhira TANAKA.
Application Number | 20210324844 17/365323 |
Document ID | / |
Family ID | 1000005750952 |
Filed Date | 2021-10-21 |
United States Patent
Application |
20210324844 |
Kind Code |
A1 |
TANAKA; Nobuhira ; et
al. |
October 21, 2021 |
PIEZOELECTRIC PUMP
Abstract
A piezoelectric pump includes a first top board, a second top
board, a diaphragm, a first side wall, a second side wall, a first
valve, and a second valve. The first valve has an annular shape to
surround the first aperture while being spaced apart from the first
aperture and the second aperture, and is disposed in the first pump
chamber between the first aperture and the second aperture when
viewed in a plan. The second valve has an annular shape to surround
the third aperture while being spaced apart from the third aperture
and the fourth aperture, and is disposed in the second pump chamber
between the third aperture and the fourth aperture when viewed in a
plan.
Inventors: |
TANAKA; Nobuhira; (Kyoto,
JP) ; FUJISAKI; Masaaki; (Kyoto, JP) |
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Applicant: |
Name |
City |
State |
Country |
Type |
Murata Manufacturing Co., Ltd. |
Kyoto |
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JP |
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Family ID: |
1000005750952 |
Appl. No.: |
17/365323 |
Filed: |
July 1, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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PCT/JP2020/001333 |
Jan 16, 2020 |
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17365323 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04B 43/046
20130101 |
International
Class: |
F04B 43/04 20060101
F04B043/04 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 27, 2019 |
JP |
2019-061038 |
Claims
1. A piezoelectric pump, comprising: a first top board having a
first aperture and a second aperture; a second top board spaced
apart from the first top board and having a third aperture and a
fourth aperture; a diaphragm disposed between the first top board
and the second top board, and having a piezoelectric element
attached thereto; a first side wall coupling the first top board
and the diaphragm to define a first pump chamber between the first
top board and the diaphragm; a second side wall coupling the second
top board and the diaphragm to define a second pump chamber between
the second top board and the diaphragm; a first valve having an
annular shape to surround the first aperture while being spaced
apart from the first aperture and the second aperture, and disposed
in the first pump chamber between the first aperture and the second
aperture when viewed in a plan from a main surface of the first top
board toward a main surface of the second top board; and a second
valve having an annular shape to surround the third aperture while
being spaced apart from the third aperture and the fourth aperture,
and disposed in the second pump chamber between the third aperture
and the fourth aperture when viewed in a plan from the main surface
of the second top board toward the main surface of the first top
board.
2. The piezoelectric pump according to claim 1, wherein the first
valve includes a first fixed portion fixed to the first top board,
and a first movable portion extending from the first fixed portion,
and wherein the second valve includes a second fixed portion fixed
to the second top board, and a second movable portion extending
from the second fixed portion.
3. The piezoelectric pump according to claim 1, wherein the first
valve includes a third fixed portion fixed to the diaphragm, and a
third movable portion extending from the third fixed portion, and
wherein the second valve includes a fourth fixed portion fixed to
the diaphragm, and a fourth movable portion extending from the
fourth fixed portion.
4. The piezoelectric pump according to claim 2, wherein the first
movable portion of the first valve is disposed on an inner side of
the first fixed portion of the first valve when viewed in a plan
from the main surface of the first top board toward the main
surface of the second top board, and wherein the second movable
portion of the second valve is disposed on an inner side of the
second fixed portion of the second valve when viewed in a plan from
the main surface of the second top board toward the main surface of
the first top board.
5. The piezoelectric pump according to claim 3, wherein the third
movable portion of the first valve is disposed on an inner side of
the third fixed portion of the first valve when viewed in a plan
from the main surface of the first top board toward the main
surface of the second top board, and wherein the fourth movable
portion of the second valve is disposed on an inner side of the
fourth fixed portion of the second valve when viewed in a plan from
the main surface of the second top board toward the main surface of
the first top board.
6. The piezoelectric pump according to claim 2, wherein the first
movable portion of the first valve is disposed on an outer side of
the first fixed portion of the first valve when viewed in a plan
from the main surface of the first top board toward the main
surface of the second top board, and wherein the second movable
portion of the second valve is disposed on an outer side of the
second fixed portion of the second valve when viewed in a plan from
the main surface of the second top board toward the main surface of
the first top board.
7. The piezoelectric pump according to claim 3, wherein the third
movable portion of the first valve is disposed on an outer side of
the third fixed portion of the first valve when viewed in a plan
from the main surface of the first top board toward the main
surface of the second top board, and wherein the fourth movable
portion of the second valve is disposed on an outer side of the
fourth fixed portion of the second valve when viewed in a plan from
the main surface of the second top board toward the main surface of
the first top board.
8. The piezoelectric pump according to claim 1, wherein the
diaphragm separates the first pump chamber from the second pump
chamber to disable connection between the first pump chamber and
the second pump chamber.
9. The piezoelectric pump according to claim 1, wherein the
diaphragm includes a supporter including a first main surface
having the piezoelectric element attached thereto, and the
supporter supporting the piezoelectric element, a vibrator attached
to a second main surface of the supporter at a position across from
the piezoelectric element, and a frame attached to the second main
surface of the supporter at a position between the first side wall
and the second side wall while being spaced apart from the
vibrator.
10. The piezoelectric pump according to claim 9, wherein an outer
peripheral edge of the vibrator is disposed at a position different
from a position serving as a vibration node of the vibrator.
11. The piezoelectric pump according to claim 9, wherein the
supporter comprises a material having a lower modulus of elasticity
than the vibrator.
12. The piezoelectric pump according to claim 11, wherein the
supporter is thinner than the vibrator.
13. The piezoelectric pump according to claim 2, wherein the
diaphragm separates the first pump chamber from the second pump
chamber to disable connection between the first pump chamber and
the second pump chamber.
14. The piezoelectric pump according to claim 3, wherein the
diaphragm separates the first pump chamber from the second pump
chamber to disable connection between the first pump chamber and
the second pump chamber.
15. The piezoelectric pump according to claim 4, wherein the
diaphragm separates the first pump chamber from the second pump
chamber to disable connection between the first pump chamber and
the second pump chamber.
16. The piezoelectric pump according to claim 5, wherein the
diaphragm separates the first pump chamber from the second pump
chamber to disable connection between the first pump chamber and
the second pump chamber.
17. The piezoelectric pump according to claim 6, wherein the
diaphragm separates the first pump chamber from the second pump
chamber to disable connection between the first pump chamber and
the second pump chamber.
18. The piezoelectric pump according to claim 7, wherein the
diaphragm separates the first pump chamber from the second pump
chamber to disable connection between the first pump chamber and
the second pump chamber.
19. The piezoelectric pump according to claim 2, wherein the
diaphragm includes a supporter including a first main surface
having the piezoelectric element attached thereto, and the
supporter supporting the piezoelectric element, a vibrator attached
to a second main surface of the supporter at a position across from
the piezoelectric element, and a frame attached to the second main
surface of the supporter at a position between the first side wall
and the second side wall while being spaced apart from the
vibrator.
20. The piezoelectric pump according to claim 3, wherein the
diaphragm includes a supporter including a first main surface
having the piezoelectric element attached thereto, and the
supporter supporting the piezoelectric element, a vibrator attached
to a second main surface of the supporter at a position across from
the piezoelectric element, and a frame attached to the second main
surface of the supporter at a position between the first side wall
and the second side wall while being spaced apart from the
vibrator.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This is a continuation of International Application No.
PCT/JP2020/001333 filed on Jan. 16, 2020 which claims priority from
Japanese Patent Application No. 2019-061038 filed on Mar. 27, 2019.
The contents of these applications are incorporated herein by
reference in their entireties.
BACKGROUND OF THE DISCLOSURE
Field of the Disclosure
[0002] The present disclosure relates to a piezoelectric pump.
Description of the Related Art
[0003] Piezoelectric pumps including a piezoelectric element have
been disclosed thus far (refer to, for example, Patent Document
1).
[0004] A piezoelectric pump according to Patent Document 1 includes
a diaphragm to which a piezoelectric element is bonded, a first top
board and a second top board disposed on opposite main surfaces of
the diaphragm, a first side wall, and a second side wall. The first
side wall couples the diaphragm to the first top board, and the
second side wall couples the diaphragm to the second top board. A
space defined by the first top board, the diaphragm, and the first
side wall serves as a first pump chamber. A space defined by the
second top board, the diaphragm, and the second side wall serves as
a second pump chamber. Both pump chambers are separated by the
diaphragm.
[0005] The first top board has an inlet port and an outlet port.
The second top board also has an inlet port and an outlet port. The
respective outlet ports are formed from multiple apertures, and
selectively opened or closed with a film-shaped valve disposed in
the pump chambers.
[0006] When the piezoelectric element in such a structure receives
alternating current (AC) power, the piezoelectric element causes
unimorph bending deformation, and causes pressure changes in the
internal spaces in the first pump chamber and the second pump
chamber. In accordance with the pressure changes, the valves
disposed in the pump chambers alternately move between the position
where it opens the outlet port and the position where it closes the
outlet port.
[0007] Patent Document 1: U.S. Patent Application Publication No.
2015/0023821
BRIEF SUMMARY OF THE DISCLOSURE
[0008] Each valve that opens or closes the outlet port repeatedly
collides against the edge of the outlet port. The repeated
collision of the valve against the edge of the outlet port may
damage the valve, and degrade the performance of the valve. This
may lower the reliability of the piezoelectric pump.
[0009] An object of the present disclosure is to solve the above
problem, and to provide a piezoelectric pump with improved
reliability.
[0010] To achieve the above object, the piezoelectric pump
according to the present disclosure includes a first top board in
which a first aperture and a second aperture are formed, a second
top board that is spaced apart from the first top board and in
which a third aperture and a fourth aperture are formed, a
diaphragm disposed between the first top board and the second top
board, and to which a piezoelectric element is attached, a first
side wall coupling the first top board and the diaphragm to define
a first pump chamber between the first top board and the diaphragm,
a second side wall coupling the second top board and the diaphragm
to define a second pump chamber between the second top board and
the diaphragm, a first valve having an annular shape to surround
the first aperture while being spaced apart from the first aperture
and the second aperture, and disposed in the first pump chamber
between the first aperture and the second aperture when viewed in a
plan from a main surface of the first top board toward a main
surface of the second top board, and a second valve having an
annular shape to surround the third aperture while being spaced
apart from the third aperture and the fourth aperture, and disposed
in the second pump chamber between the third aperture and the
fourth aperture when viewed in a plan from the main surface of the
second top board toward the main surface of the first top
board.
[0011] The piezoelectric pump according to the present disclosure
can improve the reliability.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0012] FIG. 1 is a perspective view of a piezoelectric pump
according to a first embodiment.
[0013] FIG. 2 is an exploded perspective view of the piezoelectric
pump according to the first embodiment.
[0014] FIG. 3 is a cross-sectional view of the piezoelectric pump
taken along line A-A in FIG. 1.
[0015] FIG. 4 is a plan view of the piezoelectric pump according to
the first embodiment illustrating the positional relationship
between a first aperture, second apertures, and a first valve.
[0016] FIG. 5 is a plan view of the piezoelectric pump according to
the first embodiment illustrating the positional relationship
between a third aperture, fourth apertures, and a second valve.
[0017] FIG. 6 is a plan view of the top surface of the diaphragm
according to the first embodiment.
[0018] FIG. 7 is a plan view of the rear surface of the
piezoelectric element according to the first embodiment.
[0019] FIG. 8A is a cross-sectional view of the piezoelectric pump
according to the first embodiment in a driven state.
[0020] FIG. 8B is a cross-sectional view of the piezoelectric pump
according to the first embodiment in a driven state.
[0021] FIG. 8C is a cross-sectional view of the piezoelectric pump
according to the first embodiment in a driven state.
[0022] FIG. 8D is a cross-sectional view of the piezoelectric pump
according to the first embodiment in a driven state.
[0023] FIG. 9 is a cross-sectional view of a schematic structure of
a piezoelectric pump according to a second embodiment.
[0024] FIG. 10 is a cross-sectional view of a schematic structure
of a piezoelectric pump according to a third embodiment.
[0025] FIG. 11A is a plan view of the piezoelectric pump according
to the third embodiment illustrating the positional relationship
between first apertures, second apertures, and a first valve.
[0026] FIG. 11B is a plan view of the piezoelectric pump according
to the third embodiment illustrating the positional relationship
between third apertures, fourth apertures, and a second valve.
DETAILED DESCRIPTION OF THE DISCLOSURE
[0027] A first aspect of the present disclosure provides a
piezoelectric pump that includes a first top board in which a first
aperture and a second aperture are formed, a second top board that
is spaced apart from the first top board and in which a third
aperture and a fourth aperture are formed, a diaphragm disposed
between the first top board and the second top board, and to which
a piezoelectric element is attached, a first side wall coupling the
first top board and the diaphragm to define a first pump chamber
between the first top board and the diaphragm, a second side wall
coupling the second top board and the diaphragm to define a second
pump chamber between the second top board and the diaphragm, a
first valve having an annular shape to surround the first aperture
while being spaced apart from the first aperture and the second
aperture, and disposed in the first pump chamber between the first
aperture and the second aperture when viewed in a plan from a main
surface of the first top board toward a main surface of the second
top board, and a second valve having an annular shape to surround
the third aperture while being spaced apart from the third aperture
and the fourth aperture, and disposed in the second pump chamber
between the third aperture and the fourth aperture when viewed in a
plan from the main surface of the second top board toward the main
surface of the first top board.
[0028] In this structure, the valves are spaced apart from the
apertures, prevented from colliding against the edges of the
apertures, and thus prevented from being damaged. This structure
can thus extend the lives of the valves, and improve the
reliability of the piezoelectric pump.
[0029] A second aspect of the present disclosure provides the
piezoelectric pump according to the first aspect, wherein the first
valve includes a first fixed portion fixed to the first top board,
and a first movable portion extending from the first fixed portion,
and wherein the second valve includes a second fixed portion fixed
to the second top board, and a second movable portion extending
from the second fixed portion. In this structure, the valves are
fixed to the top boards. This structure can reduce the vibrations
of the fixed portions of the valves more than when the valves are
fixed to the vibrator. This structure can thus reduce an excessive
vibration loss, and achieve large vibration displacement, a high
flow rate, and high pressure characteristics.
[0030] A third aspect of the present disclosure provides the
piezoelectric pump according to the first aspect, wherein the first
valve includes a third fixed portion fixed to the diaphragm, and a
third movable portion extending from the third fixed portion, and
wherein the second valve includes a fourth fixed portion fixed to
the diaphragm, and a fourth movable portion extending from the
fourth fixed portion. In this structure, the valves are fixed to
the diaphragm. This structure can reduce flow path resistance near
the top boards, and achieve a high flow rate.
[0031] A fourth aspect of the present disclosure provides the
piezoelectric pump according to the second aspect, wherein the
first movable portion of the first valve is disposed on an inner
side of the first fixed portion of the first valve when viewed in a
plan from the main surface of the first top board toward the main
surface of the second top board, and wherein the second movable
portion of the second valve is disposed on an inner side of the
second fixed portion of the second valve when viewed in a plan from
the main surface of the second top board toward the main surface of
the first top board. This structure can accelerate a flow of air
that flows from the outside of the piezoelectric pump into the
first pump chamber through the second aperture and then flows out
through the first aperture, and a flow of air that flows from the
outside of the piezoelectric pump into the second pump chamber
through the fourth aperture and then flows out through the third
aperture.
[0032] A fifth aspect of the present disclosure provides the
piezoelectric pump according to the third aspect, wherein the third
movable portion of the first valve is disposed on an inner side of
the third fixed portion of the first valve when viewed in a plan
from the main surface of the first top board toward the main
surface of the second top board, and wherein the fourth movable
portion of the second valve is disposed on an inner side of the
fourth fixed portion of the second valve when viewed in a plan from
the main surface of the second top board toward the main surface of
the first top board. This structure can accelerate a flow of air
that flows from the outside of the piezoelectric pump into the
first pump chamber through the second aperture and then flows out
through the first aperture, and a flow of air that flows from the
outside of the piezoelectric pump into the second pump chamber
through the fourth aperture and then flows out through the third
aperture.
[0033] A sixth aspect of the present disclosure provides the
piezoelectric pump according to the second aspect, wherein the
first movable portion of the first valve is disposed on an outer
side of the first fixed portion of the first valve when viewed in a
plan from the main surface of the first top board toward the main
surface of the second top board, and wherein the second movable
portion of the second valve is disposed on an outer side of the
second fixed portion of the second valve when viewed in a plan from
the main surface of the second top board toward the main surface of
the first top board. This structure can accelerate a flow of air
that flows from the outside of the piezoelectric pump into the
first pump chamber through the first aperture and then flows out
through the second aperture, and a flow of air that flows from the
outside of the piezoelectric pump into the second pump chamber
through the third aperture and then flows out through the fourth
aperture.
[0034] A seventh aspect of the present disclosure provides the
piezoelectric pump according to the third aspect, wherein the third
movable portion of the first valve is disposed on an outer side of
the third fixed portion of the first valve when viewed in a plan
from the main surface of the first top board toward the main
surface of the second top board, and wherein the fourth movable
portion of the second valve is disposed on an outer side of the
fourth fixed portion of the second valve when viewed in a plan from
the main surface of the second top board toward the main surface of
the first top board. This structure can accelerate a flow of air
that flows from the outside of the piezoelectric pump into the
first pump chamber through the first aperture and then flows out
through the second aperture, and a flow of air that flows from the
outside of the piezoelectric pump into the second pump chamber
through the third aperture and then flows out through the fourth
aperture.
[0035] An eighth aspect of the present disclosure provides a
piezoelectric pump according to any of the first to seventh
aspects, wherein the diaphragm separates the first pump chamber
from the second pump chamber to disable connection between the
first pump chamber and the second pump chamber. This structure can
cause separate airflows in the first pump chamber and the second
pump chamber.
[0036] A ninth aspect of the present disclosure provides a
piezoelectric pump according to any one of the first to eighth
aspects, wherein the diaphragm includes a supporter including a
first main surface to which the piezoelectric element is attached,
and the supporter supporting the piezoelectric element, a vibrator
attached to a second main surface of the supporter at a position
across from the piezoelectric element, and a frame attached to the
second main surface of the supporter at a position between the
first side wall and the second side wall while being spaced apart
from the vibrator. In this structure, the diaphragm can be made of
multiple materials.
[0037] A tenth aspect of the present disclosure provides the
piezoelectric pump according to the ninth aspect, wherein an outer
peripheral edge of the vibrator is disposed at a position different
from a position serving as a vibration node of the vibrator. In
this structure, the outer peripheral edge of the vibrator can
reliably vibrate, so that vibrations of the piezoelectric element
are prevented from being transmitted to side walls or top boards
constituting the exterior of the piezoelectric pump. This structure
can thus reduce vibration leakage, and increase displacement with
the vibrator.
[0038] An eleventh aspect of the present disclosure provides the
piezoelectric pump according to the ninth or tenth aspect, wherein
the supporter is made of a material having a lower modulus of
elasticity than the vibrator. Such a structure can reduce the
leakage of the vibrations.
[0039] A twelfth aspect of the present disclosure provides the
piezoelectric pump according to the eleventh aspect, wherein the
supporter is thinner than the vibrator. Such a structure can reduce
the leakage of the vibrations.
[0040] Hereinbelow, embodiments of the present disclosure will be
described in detail with reference to the drawings.
First Embodiment
[0041] FIGS. 1 to 3 are views illustrating a schematic structure of
a piezoelectric pump 2 according to a first embodiment. FIG. 1 is a
perspective view of the piezoelectric pump 2 according to the first
embodiment, FIG. 2 is an exploded perspective view of the
piezoelectric pump 2, and FIG. 3 is a vertical cross-sectional view
of the piezoelectric pump 2 (cross-sectional view taken along line
A-A in FIG. 1).
[0042] The piezoelectric pump 2 is a pump device (may be also
referred to as "Microblower" or "Micropump") that transports air
using a piezoelectric element 10 (FIGS. 2 and 3). The piezoelectric
pump 2 vibrates the piezoelectric element 10 at high speed to suck
air through second apertures 21, serving as inlet ports, and to
discharge air through a first aperture 20, serving as an outlet
port. Similarly, the piezoelectric pump 2 is a pump that sucks air
through fourth apertures 23, serving as inlet ports, and discharges
air through a third aperture 22, serving as an outlet port.
[0043] As illustrated in FIGS. 2 and 3, the piezoelectric pump 2
includes a first top board 4, a second top board 6, a diaphragm 8,
a piezoelectric element 10, a first side wall 12, a second side
wall 14, a first valve 16, and a second valve 18. The piezoelectric
pump 2 has a structure where the piezoelectric element 10 is bonded
to the diaphragm 8. The piezoelectric element 10 causes unimorph
bending deformation upon receiving AC power. The piezoelectric pump
2 includes, inside thereof, the first valve 16 and the second valve
18 serving as valves.
[0044] The first top board 4 and the second top board 6
respectively constitute a top surface and a rear surface of the
piezoelectric pump 2. The first top board 4 and the second top
board 6 are disk-shaped members, and spaced apart from each other.
The first top board 4 and the second top board 6 are made of, for
example, metal such as stainless steel, or resin such as
polyphenylene sulfide (PPS).
[0045] The first top board 4 includes a first aperture 20 and
second apertures 21. The first aperture 20 is disposed at the
center portion of the first top board 4, and the multiple second
apertures 21 are annularly arranged to surround the first aperture
20. In the first embodiment, the first aperture 20 functions as an
outlet port, and the second apertures 21 function as inlet
ports.
[0046] The second top board 6 includes a third aperture 22 and
fourth apertures 23. The third aperture 22 is disposed at the
center portion of the second top board 6, and the multiple fourth
apertures 23 are annularly arranged to surround the third aperture
22. In the first embodiment, the third aperture 22 functions as an
outlet port, and the fourth apertures 23 function as inlet
ports.
[0047] The diaphragm 8 is a member disposed between the first top
board 4 and the second top board 6. The piezoelectric element 10 is
attached to the diaphragm 8. The diaphragm 8 includes a supporter
26, a vibrator 28, and a frame 30. In the first embodiment, the
supporter 26, the vibrator 28, and the frame 30 are separate
members.
[0048] The supporter 26 is a substantially disk-shaped member to
which the piezoelectric element 10 is attached and that supports
the piezoelectric element 10. The supporter 26 is made of an
insulating material such as polyimide.
[0049] As illustrated in FIG. 3, the supporter 26 has a first main
surface 26A and a second main surface 26B. The piezoelectric
element 10 is attached to the first main surface 26A, and the
vibrator 28 and the frame 30 are attached to the second main
surface 26B.
[0050] The vibrator 28 is a disk-shaped member disposed across from
the piezoelectric element 10. The vibrator 28 has a function of
vibrating together with the piezoelectric element 10.
[0051] The frame 30 is an annular member forming an outer frame of
the diaphragm 8. The frame 30 is disposed on the outer side of the
vibrator 28 at a distance from the vibrator 28. The frame 30 is
disposed to be held between the first side wall 12 and the second
side wall 14. The frame 30 constitutes the side wall of the
piezoelectric pump 2, together with the first side wall 12 and the
second side wall 14.
[0052] The vibrator 28 and the frame 30 are made of metal such as
stainless steel or aluminum.
[0053] The piezoelectric element 10 is located to overlap the
vibrator 28 when viewed in a plan. As illustrated in FIG. 3, the
piezoelectric element 10 is located to overlap the first aperture
20 and the first top board 4 around the first aperture 20 when
viewed in a plan. Similarly, the piezoelectric element 10 is
located to overlap the third aperture 22 and the second top board 6
around the third aperture 22 when viewed in a plan.
[0054] The first side wall 12 and the second side wall 14
constitute the side wall of the piezoelectric pump 2. The first
side wall 12 and the second side wall 14 are annular members each
having a circular opening at the center portion. The first side
wall 12 and the second side wall 14 are made of, for example, metal
or resin.
[0055] As illustrated in FIG. 3, the first side wall 12 couples the
first top board 4 to the diaphragm 8 to define a first pump chamber
32 between the first top board 4 and the diaphragm 8. The second
side wall 14 couples the second top board 6 to the diaphragm 8 to
define a second pump chamber 34 between the second top board 6 and
the diaphragm 8.
[0056] The first pump chamber 32 and the second pump chamber 34 are
separated by the supporter 26 of the diaphragm 8. The supporter 26
according to the first embodiment separates the first pump chamber
32 from the second pump chamber 34 to disable connection between
the first pump chamber 32 and the second pump chamber 34.
[0057] The first valve 16 and the second valve 18 are valves that
control airflow inside the piezoelectric pump 2. The first valve 16
and the second valve 18 are annular members each having a circular
opening at the center portion. The first valve 16 is disposed in
the first pump chamber 32, and the second valve 18 is disposed in
the second pump chamber 34. The first valve 16 and the second valve
18 are made of, for example, resin such as polyimide, PET, or
PPS.
[0058] As illustrated in FIG. 3, the first valve 16 is disposed
between the first aperture 20 and the second apertures 21 when
viewed in a plan. Similarly, the second valve 18 is disposed
between the third aperture 22 and the fourth apertures 23 when
viewed in a plan.
[0059] As illustrated in FIG. 3, the first valve 16 includes a
fixed portion (first fixed portion) 16A and a movable portion
(first movable portion) 16B. The fixed portion 16A is a portion
fixed to the first top board 4, and the movable portion 16B is a
movable portion extending from the fixed portion 16A. The movable
portion 16B functions as a free end (open end) without being fixed
to any member.
[0060] The movable portion 16B is disposed closer to the first
aperture 20 or the center portion than the fixed portion 16A is.
This arrangement reduces airflow that flows outward from the center
in the first pump chamber 32, and accelerates a reverse flow F1
that flows toward the center from the outer side.
[0061] Similarly, the second valve 18 includes a fixed portion
(second fixed portion) 18A and a movable portion (second movable
portion) 18B. The fixed portion 18A is a portion fixed to the
second top board 6, and the movable portion 18B is a movable
portion extending from the fixed portion 18A. The movable portion
18B functions as a free end without being fixed to any member.
[0062] The movable portion 18B is disposed closer to the third
aperture 22 or the center portion than the fixed portion 18A is.
This arrangement reduces airflow that flows outward from the center
in the second pump chamber 34, and accelerates a reverse flow F2
that flows toward the center from the outer side.
[0063] The acceleration of the flow F1 in the first pump chamber 32
and the flow F2 in the second pump chamber 34 causes flows F3 to
F6, as illustrated in FIG. 3. The flow F3 is air that flows into
the first pump chamber 32 from the outer side of the piezoelectric
pump 2 through the second apertures 21. The flow F4 is air that
flows out of the first pump chamber 32 to the outer side of the
piezoelectric pump 2 through the first aperture 20. Similarly, the
flow F5 is air that flows into the second pump chamber 34 from the
outer side of the piezoelectric pump 2 through the fourth apertures
23. The flow F6 is air that flows out of the second pump chamber 34
to the outer side of the piezoelectric pump 2 through the third
aperture 22. FIG. 3 illustrates the flows F1 to F6 with arrows as
general flows inside the piezoelectric pump 2.
[0064] With reference to FIGS. 4 and 5, the relationship between
the first valve 16 and the apertures 20 and 21 and the relationship
between the second valve 18 and the apertures 22 and 23 will be
described. FIG. 4 is a plan view of the piezoelectric pump 2
illustrating the positional relationship between the first aperture
20, the second apertures 21, and the first valve 16. FIG. 5 is a
plan view of the piezoelectric pump 2 illustrating the positional
relationship between the third aperture 22, the fourth apertures
23, and the second valve 18.
[0065] As illustrated in FIG. 4, the first aperture 20 is disposed
on the inner side of the first valve 16 when viewed in a plan, and
the second apertures 21 are disposed on the outer side of the first
valve 16 when viewed in a plan. The first valve 16 has an annular
shape to surround the first aperture 20 at a distance D1 from the
first aperture 20. The first valve 16 is also spaced apart at a
distance D2 from the second apertures 21. In this structure, the
first valve 16 is spaced apart from the first aperture 20 and the
second apertures 21. Thus, even when the movable portion 16B of the
first valve 16 moves at high speed while the piezoelectric pump 2
is being driven, the movable portion 16B is prevented from
colliding against the edge of the first aperture 20 and the edges
of the second apertures 21. This structure where the movable
portion 16B of the first valve 16 is prevented from colliding
against the edges of the apertures 20 and 21 can reduce the damages
on the first valve 16, and extend the life of the first valve 16.
Thus, the reliability of the piezoelectric pump 2 can be
improved.
[0066] Similarly, as illustrated in FIG. 5, the third aperture 22
is disposed on the inner side of the second valve 18 when viewed in
a plan, and the fourth apertures 23 are disposed on the outer side
of the second valve 18 when viewed in a plan. The second valve 18
has an annular shape to surround the third aperture 22 at the
distance D1 from the third aperture 22. The second valve 18 is also
spaced apart at the distance D2 from the fourth apertures 23. In
this structure, as in the first valve 16, the movable portion 18B
of the second valve 18 is prevented from colliding against the edge
of the third aperture 22 and the edges of the fourth apertures 23.
This structure can reduce the damages on the second valve 18, and
extend the life of the second valve 18. Thus, the reliability of
the piezoelectric pump 2 can be improved.
[0067] Referring back to FIG. 3, the first aperture 20 is disposed
on the inner side of an outer peripheral edge 27 of the vibrator 28
when viewed in a plan, and the third aperture 22 is disposed on the
inner side of the outer peripheral edge 27 of the vibrator 28 when
viewed in a plan. Vibrations of the vibrator 28 change the pressure
around the first aperture 20 and the third aperture 22, and
increase the flow rate of a fluid that flows out from the first
pump chamber 32 and the second pump chamber 34 in response to the
vibrations of the vibrator 28.
[0068] The second apertures 21 are disposed on the inner side of
the outer peripheral edge 27 of the vibrator 28 when viewed in a
plan, and the fourth apertures 23 are disposed on the inner side of
the outer peripheral edge 27 of the vibrator 28 when viewed in a
plan. Vibrations of the vibrator 28 change the pressure around the
second apertures 21 and the fourth apertures 23, and increase the
flow rate of a fluid that flows into the first pump chamber 32 and
the second pump chamber 34 in response to the vibrations of the
vibrator 28.
[0069] Wires 36 connected to the piezoelectric element 10 will now
be described with reference to FIGS. 6 and 7. FIG. 6 is a plan view
of the top surface of the supporter 26 in the diaphragm 8 on which
the wires 36 are disposed. FIG. 7 is a plan view of the rear
surface of the piezoelectric element 10.
[0070] As illustrated in FIG. 6, a first wire 44 and a second wire
46, included in the wires 36, are disposed on the top surface of
the supporter 26. As described above, the supporter 26 itself is
made of an insulating material, and the first wire 44 and the
second wire 46 disposed on the supporter 26 are electrically
insulated from each other. The first wire 44 and the second wire 46
disposed on the supporter 26 made of an insulating material can
reduce the risk of disconnection.
[0071] The first wire 44 and the second wire 46 are connected to a
driving circuit (not illustrated) disposed outside of the
piezoelectric pump 2.
[0072] Although not illustrated, a portion where the first wire 44
and the second wire 46 are in contact with the first side wall 12
and the second side wall 14 is coated with an insulating material
to avoid electrical connection with the side walls 12 and 14.
[0073] As illustrated in FIG. 7, a first electrode 38 and a second
electrode 40 are formed on the rear surface of the piezoelectric
element 10. An insulating region 42 is disposed between the first
electrode 38 and the second electrode 40 to electrically insulate
the first electrode 38 from the second electrode 40. The first
electrode 38 is disposed on most part of the rear surface of the
piezoelectric element 10, and the second electrode 40 is disposed
on a small portion of the rear surface of the piezoelectric element
10. The second electrode 40 is disposed on the entirety of the top
surface (not illustrated) of the piezoelectric element 10. FIG. 7
illustrates a portion of the second electrode 40 folded back to the
rear surface.
[0074] To place the rear surface of the piezoelectric element 10
illustrated in FIG. 7 on the supporter 26 of the diaphragm 8
illustrated in FIG. 6, the first electrode 38 is brought into
contact with the first wire 44 and, concurrently, the second
electrode 40 is brought into contact with the second wire 46. AC
power can be fed to the first electrode 38 and the second electrode
40 through two wires, that is, the first wire 44 and the second
wire 46, respectively. Thus, this structure can cause the
piezoelectric element 10 to perform desired bending movement.
[0075] The operation of the piezoelectric pump 2 with the above
structure will be described with reference to FIG. 8A to FIG. 8D.
FIG. 8A to FIG. 8D are vertical cross-sectional views illustrating
the piezoelectric pump 2 in the respective states when being
driven. FIG. 8A to FIG. 8D illustrate the diaphragm 8 in a
simplified manner.
[0076] FIG. 8A illustrates the state where the center portion of
the diaphragm 8 is recessed at maximum toward the second top board
6. FIG. 8B illustrates the state where the center portion of the
diaphragm 8 is moved toward the first top board 4 from the state
illustrated in FIG. 8A to flatten.
[0077] As illustrated in FIGS. 8A and 8B, when the center portion
of the diaphragm 8 moves from the second top board 6 toward the
first top board 4 (arrow X1), air at the center portion of the
first pump chamber 32 is pushed toward the first top board 4 to
cause a flow F7 discharged from the first aperture 20. Here, a flow
F8 of air that flows outward from the center portion of the first
pump chamber 32 is blocked by the first valve 16. Thus, the flow F7
has a relatively high flow rate.
[0078] On the other hand, the space on the outer side in the first
pump chamber 32 extends to the lower side, and thus causes a
negative pressure. This negative pressure causes a flow F9, which
flows into the first pump chamber 32 from the outside of the
piezoelectric pump 2 through the second apertures 21. Here, a flow
F10 of air that flows from the outer side in the first pump chamber
32 toward the center portion is prevented from being blocked by the
first valve 16.
[0079] The space in the second pump chamber 34 at the center
portion extends to the upper side, and thus causes a negative
pressure. This negative pressure causes a flow F11 that flows into
the second pump chamber 34 from the outside of the piezoelectric
pump 2 through the third aperture 22. Here, a flow F12 of air that
flows outward from the center portion of the second pump chamber 34
is blocked by the second valve 18. Thus, the flow F11 has a
relatively low flow rate.
[0080] On the other hand, the space on the outer side in the second
pump chamber 34 is narrowed, and increases the pressure. This high
pressure causes a flow F13 that flows out of the piezoelectric pump
2 from the second pump chamber 34 through the fourth apertures 23.
Here, concurrently, a flow F14 of air that flows from the outer
side in the second pump chamber 34 toward the center portion
occurs. The flow F14 is prevented from being blocked by the second
valve 18. The second pump chamber 34 through which the flow F14
flows has a flow-path cross section larger than a flow-path cross
section of the fourth apertures 23 through which the flow F13
flows. Thus, the flow F13 has a smaller flow rate than the flow
rate of the flow F14.
[0081] FIGS. 8C and 8D illustrate the states following the state
illustrated in FIG. 8B. FIG. 8C illustrates the state where the
center portion of the diaphragm 8 is moved at maximum toward the
first top board 4 from the state illustrated in FIG. 8B. FIG. 8D
illustrates the state where the center portion of the diaphragm 8
is moved from the state illustrated in FIG. 8C toward the second
top board 6 to flatten.
[0082] As illustrated in FIGS. 8C and 8D, when the center portion
of the diaphragm 8 moves from the first top board 4 toward the
second top board 6 (arrow X2), air at the center portion of the
second pump chamber 34 is pushed toward the second top board 6 to
cause a flow F15 discharged to the outside from the third aperture
22. Here, a flow F16 of air that flows outward from the center
portion of the second pump chamber 34 is blocked by the second
valve 18. Thus, the flow F15 has a relatively high flow rate.
[0083] On the other hand, the space on the outer side in the second
pump chamber 34 extends to the upper side, and thus causes a
negative pressure. This negative pressure causes a flow F17, which
flows into the second pump chamber 34 from the outside of the
piezoelectric pump 2 through the fourth apertures 23. Here, a flow
F18 of air that flows from the outer side in the second pump
chamber 34 toward the center portion is prevented from being
blocked by the second valve 18.
[0084] The space in the first pump chamber 32 at the center portion
extends to the lower side, and thus causes a negative pressure.
This negative pressure causes a flow F19 that flows into the first
pump chamber 32 from the outside of the piezoelectric pump 2
through the first aperture 20. Here, a flow F20 of air that flows
outward from the center portion of the first pump chamber 32 is
blocked. Thus, the flow F19 has a relatively low flow rate.
[0085] On the other hand, the space on the outer side in the first
pump chamber 32 is narrowed, and increases the pressure. This high
pressure causes a flow F21 that flows out of the piezoelectric pump
2 through the second apertures 21. Here, concurrently, a flow F22
of air that flows from the outer side in the first pump chamber 32
toward the center portion occurs. The flow F22 is prevented from
being blocked by the first valve 16. The first pump chamber 32
through which the flow F22 flows has a flow-path cross section
larger than a flow-path cross section of the second apertures 21
through which the flow F21 flows. Thus, the flow F21 has a smaller
flow rate than the flow rate of the flow F22.
[0086] The sequential states illustrated in FIG. 8A to FIG. 8D are
repeated at high speed in accordance with vibration cycles of the
piezoelectric element 10. Here, with the airflow control effect of
the first valve 16, the flow rates of the flows F7 and F9
illustrated in FIGS. 8A and 8B are higher than the flow rates of
the flows F19 and F21 illustrated in FIGS. 8C and 8D. Similarly,
with the airflow control effect of the second valve 18, the flow
rates of the flows F11 and F13 illustrated in FIGS. 8A and 8B are
lower than the flow rates of the flows F15 and F17 illustrated in
FIGS. 8C and 8D. The flows F1 to F6 illustrated in FIG. 3 generally
occur inside the piezoelectric pump 2. Specifically, in the first
pump chamber 32, the flows F3, F1, and F4 of air that flows from
the outside of the piezoelectric pump 2 into the first pump chamber
32 through the second apertures 21 and then flows out through the
first aperture 20 generally occur. Similarly, in the second pump
chamber 34, the flows F5, F2, and F6 of air that flows from the
outside of the piezoelectric pump 2 into the second pump chamber 34
through the fourth apertures 23 and then flows out through the
third aperture 22 generally occur.
[0087] As illustrated in FIG. 8A to FIG. 8D, the diaphragm 8 has a
vibration node 48. The vibration node 48 is a portion that is not
displaced with vibrations of the vibrator 28 in the diaphragm 8. On
the other hand, the outer peripheral edge 27 of the vibrator 28 is
not located at the vibration node 48. This arrangement allows the
outer peripheral edge 27 of the vibrator 28 to reliably vibrate,
and prevents vibrations of the vibrator 28 from being transmitted
to the side walls 12 and 14 through the supporter 26. This
arrangement can thus prevent the leakage of the vibrations of the
piezoelectric element 10.
[0088] In the piezoelectric pump 2 according to the first
embodiment, the first valve 16 is spaced apart from the first
aperture 20 and the second apertures 21 when viewed in a plan, and
the second valve 18 is spaced apart from the third aperture 22 and
the fourth apertures 23 when viewed in a plan. In this arrangement,
the first valve 16 and the second valve 18 are spaced apart from
the respective apertures, and thus prevented from colliding against
the edges of the apertures. This structure can thus prevent the
damages on the valves 16 and 18. This structure can thus extend the
lives of the valves 16 and 18, and improve the reliability of the
piezoelectric pump 2.
[0089] In the piezoelectric pump 2 according to the first
embodiment, the first valve 16 includes the first fixed portion 16A
fixed to the first top board 4, and the first movable portion 16B
extending from the first fixed portion 16A. The second valve 18
includes the second fixed portion 18A fixed to the second top board
6, and the second movable portion 18B extending from the second
fixed portion 18A. Compared to the case where the valves 16 and 18
are fixed to the diaphragm 8, this structure where the valves 16
and 18 are respectively fixed to the top boards 4 and 6 can further
reduce the vibrations of the first fixed portion 16A of the valve
16 and the second fixed portion 18A of the valve 18. This structure
can thus reduce excessive vibration loss, and achieve large
vibration displacement, a high flow rate, and high pressure
characteristics.
[0090] In the piezoelectric pump 2 according to the first
embodiment, the first movable portion 16B of the first valve 16 is
disposed on the inner side of the first fixed portion 16A of the
first valve 16 when viewed in a plan, and the second movable
portion 18B of the second valve 18 is disposed on the inner side of
the second fixed portion 18A of the second valve 18 when viewed in
a plan. In this structure, the first valve 16 and the second valve
18 reduce outward airflow and accelerate inward airflow when viewed
in a plan, to cause the flows F1 to F6 illustrated in FIG. 3 as
general flows.
[0091] In the piezoelectric pump 2 according to the first
embodiment, the diaphragm 8 includes the supporter 26, the vibrator
28, and the frame 30. In this structure, the supporter 26, the
vibrator 28, and the frame 30 constituting the diaphragm 8 are
formed from separate members, and thus the diaphragm 8 can be made
of multiple materials. This structure can expand the range of
material and shape options.
[0092] In the first embodiment, the supporter 26 is made of a
material with a lower modulus of elasticity than the vibrator 28.
This structure can reduce the vibrations of the vibrator 28
transmitted to the side walls 12 and 14 through the supporter 26,
and thus can reduce the leakage of the vibrations.
[0093] In the first embodiment, the supporter 26 is thinner than
the vibrator 28. This structure can reduce the vibrations of the
vibrator 28 transmitted to the side walls 12 and 14 through the
supporter 26, and thus can further reduce the leakage of the
vibrations.
Second and Third Embodiments
[0094] A piezoelectric pump according to each of second and third
embodiments of the present disclosure will be described. The second
and third embodiments will be mainly described in terms of points
different from those of the first embodiment. The description that
repeats the description for the first embodiment will be
omitted.
[0095] FIG. 9 is a vertical cross-sectional view of a schematic
structure of a piezoelectric pump 60 according to a second
embodiment. FIG. 10 is a vertical cross-sectional view of a
schematic structure of a piezoelectric pump 70 according to a third
embodiment.
[0096] The second and third embodiments are different from the
first embodiment in terms of, for example, the position or
orientation of the first valve disposed in the first pump chamber
32, the position or orientation of the second valve disposed in the
second pump chamber 34, the number of the piezoelectric elements,
and the structure of the diaphragm.
Second Embodiment
[0097] As illustrated in FIG. 9, a piezoelectric pump 60 according
to the second embodiment includes a first valve 62 and a second
valve 64. Unlike in the first embodiment, the first valve 62 and
the second valve 64 are fixed to a diaphragm 66. In the second
embodiment, the diaphragm 66 also includes two supporters 68A and
68B, which vertically hold the vibrator 28 and the frame 30
therebetween. A piezoelectric element 10A is attached to the
supporter 68A, and a piezoelectric element 10B is bonded to the
supporter 68B.
[0098] As illustrated in FIG. 9, the first valve 62 is fixed to the
top surface of the supporter 68A, and the second valve 64 is fixed
to the rear surface of the supporter 68B. The first valve 62 is
fixed to the area of the top surface of the supporter 68A where the
piezoelectric element 10A is not attached, and the second valve 64
is fixed to the area of the top surface of the supporter 68B where
the piezoelectric element 10B is not attached.
[0099] As illustrated in FIG. 9, the first valve 62 includes a
third fixed portion 62A and a third movable portion 62B, and the
third movable portion 62B is disposed on the inner side of the
third fixed portion 62A when viewed in a plan. Similarly, the
second valve 64 includes a fourth fixed portion 64A and a fourth
movable portion 64B, and the fourth movable portion 64B is disposed
on the inner side of the fourth fixed portion 64A when viewed in a
plan. In such a structure, flows similar to those in the
piezoelectric pump 2 according to the first embodiment occur.
Specifically, in the first pump chamber 32, flows F30 to F32 of air
that flows in from the outside of the piezoelectric pump 60 through
the second apertures 21 and then flows out through the first
aperture 20 occur generally. Similarly, in the second pump chamber
34, flows F33 to F35 of air that flows in from the outside of the
piezoelectric pump 60 through the fourth apertures 23 and then
flows out through the third aperture 22 occur generally.
[0100] Fixing the valves 62 and 64 to the diaphragm 66 enables the
reduction of the flow path resistance near the top boards 4 and 6
in the internal space of the piezoelectric pump 60, and acquirement
of a high flow rate.
[0101] Providing the two piezoelectric elements 10A and 10B
increases the displacement of the piezoelectric elements 10A and
10B, and improves the characteristics compared to the structure
including only one piezoelectric element 10. The piezoelectric
elements 10A and 10B and the diaphragm 8 form a vertically
symmetrical shape. This structure at least partially prevents the
warpage of the diaphragm 8 in response to a temperature change, and
has stable characteristics.
Third Embodiment
[0102] As illustrated in FIG. 10, the piezoelectric pump 70
according to the third embodiment includes a first valve 72 and a
second valve 74. As with the second embodiment, the first valve 72
and the second valve 74 are respectively fixed to the supporters
68A and 68B of the diaphragm 66, but the positional relationship
between the movable portion and the fixed portion in the valves 72
and 74 is different from that in the second embodiment. In
addition, the positional relationship between first apertures 80
and second apertures 82 formed in a first top board 76 and the
positional relationship between third apertures 84 and fourth
apertures 86 formed in a second top board 78 are also different
from those in the second embodiment.
[0103] As illustrated in FIG. 10, the first valve 72 includes a
third fixed portion 72A and a third movable portion 72B, and the
third movable portion 72B is disposed on the outer side of the
third fixed portion 72A when viewed in a plan. Similarly, the
second valve 74 includes a fourth fixed portion 74A and a fourth
movable portion 74B, and the fourth movable portion 74B is disposed
on the outer side of the fourth fixed portion 74A when viewed in a
plan. The first valve 72 and the second valve 74 block inward
airflow when viewed in a plan. As illustrated in FIG. 10, in this
structure, reverse flows F40 to F42 and F43 to F45, which flow in
the directions opposite to those in the first and second
embodiments, occur generally. Specifically, in the first pump
chamber 32, flows F40 to F42 of air that flow from the outside of
the piezoelectric pump 70 into the first pump chamber 32 through
the first apertures 80 and then flows out through the second
apertures 82 can occur generally. Similarly, in the second pump
chamber 34, flows F43 to F45 of air that flows from the outside of
the piezoelectric pump 70 into the second pump chamber 34 through
the third apertures 84 and then flows out through the fourth
apertures 86 can occur generally.
[0104] With reference to FIGS. 11A and 11B, the relationship
between the valves and the apertures in the piezoelectric pump 70
according to the third embodiment will be described.
[0105] FIG. 11A is a plan view of the piezoelectric pump 70
illustrating the positional relationship between the first
apertures 80, the second apertures 82, and the first valve 72. FIG.
11B is a plan view of the piezoelectric pump 70 illustrating the
positional relationship between the third apertures 84, the fourth
apertures 86, and the second valve 74.
[0106] As illustrated in FIG. 11A, the first apertures 80 and the
second apertures 82 are multiple apertures. The multiple first
apertures 80 and the multiple second apertures 82 are arranged in
circles when viewed in a plan. The multiple first apertures 80 are
arranged on the inner side of the first valve 72, and the multiple
second apertures 82 are arranged on the outer side of the first
valve 72. Specifically, the diameter of the circumference on which
the first apertures 80 are arranged is smaller than the diameter of
the circumference on which the second apertures 82 are arranged. In
this arrangement, the first valve 72 is disposed between the first
apertures 80 and the second apertures 82 when viewed in a plan, to
have an annular shape surrounding the first apertures 80 while
being spaced at a distance D3 from the first apertures 80 and a
distance D4 from the second apertures 82.
[0107] This arrangement where the first valve 72 is spaced at the
distances D3 and D4 from the first apertures 80 and the second
apertures 82 can prevent the first valve 72 from colliding against
the edges of the apertures 80 and 82. This structure can thus
reduce the damages on the first valve 72, extend the life of the
first valve 72, and improve the reliability of the piezoelectric
pump 70.
[0108] Similarly, as illustrated in FIG. 11B, the third apertures
84 and the fourth apertures 86 are multiple apertures. The multiple
third apertures 84 and the multiple fourth apertures 86 are
arranged in circles when viewed in a plan. The multiple third
apertures 84 are arranged on the inner side of the second valve 74,
and the multiple fourth apertures 86 are arranged on the outer side
of the second valve 74. Specifically, the diameter of the
circumference on which the third apertures 84 are arranged is
smaller than the diameter of the circumference on which the fourth
apertures 86 are arranged. In this arrangement, the second valve 74
is disposed between the third apertures 84 and the fourth apertures
86 when viewed in a plan, to have an annular shape surrounding the
third apertures 84 while being spaced at the distance D3 from the
third apertures 84 and the distance D4 from the fourth apertures
86.
[0109] This arrangement where the second valve 74 is spaced at the
distances D3 and D4 from the third apertures 84 and the fourth
apertures 86 can prevent the second valve 74 from colliding against
the edges of the apertures 84 and 86. This structure can thus
reduce the damages on the second valve 74, extend the life of the
second valve 74, and improve the reliability of the piezoelectric
pump 70.
[0110] This structure where the apertures 80, 82, 84, and 86 formed
from multiple apertures can reduce the flow path resistance at each
aperture, and achieve a high flow rate.
[0111] The present disclosure has been described thus far using the
first to third embodiments as examples. However, the present
disclosure is not limited to the first to third embodiments.
Although the supporter 26, the vibrator 28, and the frame 30
constituting the diaphragm 8 according to the first embodiment are
described as being separate members, this is not the only possible
structure. For example, the diaphragm 8 may be a single integrated
body.
[0112] The present disclosure has been fully described in relation
to preferable embodiments with reference to the appended drawings.
However, various changes or modifications are apparent to persons
having ordinary skill in the art. It should be understood that such
changes or modifications are included in the scope of the present
disclosure defined by the appended scope of claims without
departing from the scope of the disclosure. Any combination of
components between different embodiments or any change in order of
the components may be made without departing from the scope and
idea of the present disclosure.
[0113] The present disclosure is applicable to a piezoelectric pump
including a piezoelectric element.
[0114] 2 piezoelectric pump
[0115] 4 first top board
[0116] 6 second top board
[0117] 9 diaphragm
[0118] 10 piezoelectric element
[0119] 12 first side wall
[0120] 14 second side wall
[0121] 16 first valve
[0122] 16A fixed portion (first fixed portion)
[0123] 16B movable portion (first movable portion)
[0124] 18 second valve
[0125] 18A fixed portion (second fixed portion)
[0126] 18B movable portion (second movable portion)
[0127] 20 first aperture
[0128] 21 second aperture
[0129] 22 third aperture
[0130] 23 fourth aperture
[0131] 26 supporter
[0132] 26A first main surface
[0133] 26B second main surface
[0134] 27 outer peripheral edge
[0135] 28 vibrator
[0136] 30 frame
[0137] 32 first pump chamber
[0138] 34 second pump chamber
[0139] 36 wire
[0140] 38 first electrode
[0141] 40 second electrode
[0142] 42 insulating region
[0143] 44 first wire
[0144] 46 second wire
[0145] 48 vibration node
[0146] 60 piezoelectric pump
[0147] 62 first valve
[0148] 62A third fixed portion
[0149] 62B third movable portion
[0150] 64 second valve
[0151] 64A fourth fixed portion
[0152] 64B fourth movable portion
[0153] 66 diaphragm
[0154] 68A, 68B supporter
[0155] 70 piezoelectric pump
[0156] 72 first valve
[0157] 72A third fixed portion
[0158] 72B third movable portion
[0159] 74 second valve
[0160] 74A fourth fixed portion
[0161] 74B fourth movable portion
[0162] 76 first top board
[0163] 78 second top board
[0164] 80 first aperture
[0165] 82 second aperture
[0166] 84 third aperture
[0167] 86 fourth aperture
[0168] D1 to D4 distance
[0169] F1 to F22, F30 to F35, F40 to F45 flow
* * * * *